package main

import . "fmt"
import . "sort"

func main() {
	var n, m int
	Scan(&n,&m)
	type X struct { v,w int }
	xs := make([]*X, 0, n)
	for i := 0; i < n; i++ {
		x := new(X)
		Scan(&x.v, &x.w)
		if x.w <= m {
			xs = append(xs, x)
		}
	}
	Slice(xs, func(i, j int) bool {
		return xs[i].v < xs[j].v
	})
	type Y struct { min, sum int }
	less := func(y1, y2 *Y) bool {
		s1 := y1.min*y1.sum
		s2 := y2.min*y2.sum
		if s1 < s2 {
			return true
		} else if s1 > s2 {
			return false
		} else {
			return y1.min<y2.min
		}
	}
	kn := make([]*Y, m+1)
	for _, x := range xs {
		for i := m; i >= 0; i-- {
			if kn[i] == nil || i+x.w > m {
				continue
			}
			y := &Y{ min(kn[i].min, x.v), kn[i].sum+x.v }
			if z := kn[i+x.w]; z == nil || less(z, y) {
				kn[i+x.w] = y
			}
		}
		yy := &Y{ x.v, x.v }
		if z := kn[x.w]; z == nil || less(z, yy) {
			kn[x.w] = yy
		}
	}
	ans := 0
	for _, y := range kn {
		if y != nil {
			ans = max(ans, y.min*y.sum)
		}
	}
	Println(ans)
}